Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects a...Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects are major factors in fragmented landscapes. Here, we examine area and edge effects and their interaction, on ensembles of arthropods associated to native vegetation in a fragmented Chaco Serrano forest. We analyzed family richness and community composition of herbivores, predators, and parasitoids on three native plant species in 12 fragments of varying size and at edge/interior positions. We also looked for indicator families by using Indicator Species Analysis. Loss of family richness with the reduction of forest fragment area was observed for the three functional groups, with sirnilar magnitude. Herbivores were richer at the edges without interaction between edge and area effects, whereas predators were not affected by edge/interior position and parasitoid richness showed an interaction between area and position, with a steeper area slope at the edges. Family composition of herbivore, predator, and parasitoid assemblages was also affected by forest area and/or edge/interior situation. We found three indicator families for large remnants and five for edges. Our results support the key role of forest area for conservation of arthropods taxonomic and functional diversity in a highly threatened region, and emphasize the need to understand the interactions between area and edge effects on such diversity.展开更多
Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analy...Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analyzed insects sampled with pan traps in 9 landscapes （at 5 scales, in 100-500 m diameter circles） comprising cultivated fields and Chaco Serrano forests, at overall community and taxonomic order level. In total 7043 specimens and 456 species of hexapods were captured, with abundance and richness being directly related to forest cover at 500 m and higher at edges in comparison with forest interior. Community composition also varied with forest cover and edge^interior location. Different responses were detected among the 8 dominant orders. Collembola, Hemiptera, and Orthoptera richness and^or abundance were positively related to forest cover at the larger scale, while Thysanoptera abundance increased with forest cover only at the edge. Hymenoptera abundance and richness were negatively related to forest cover at 100 m. Coleoptera, Diptera, and Hymenoptera were more diverse and abundant at the forest edge. The generally negative influence of forest loss on insect communities could have functional consequences for both natural and cultivated systems, and highlights the relevance of forest conservation. Higher diversity at the edges could result from the simultaneous presence of forest and matrix species, although ＂resource mapping＂ might be involved for orders that were richer and more abundant at edges. Adjacent crops could benefit from forest proximity since natural enemies and pollinators are well represented in the orders showing nositive edge effects.展开更多
The objective of this study consisted in the characterization of morphological variability presented in the Prosopis population in the corridor that unites the semiarid with the arid region in Argentina. In this regio...The objective of this study consisted in the characterization of morphological variability presented in the Prosopis population in the corridor that unites the semiarid with the arid region in Argentina. In this region, four species of Prosopis get in contact (P. chilensis, P. flexuosa, P. alba and P. nigra). Due to the fact that these species make fertile hybrids, this corridor has an enormous diversity. The mother’s allowed the differentiation of five morphologic groups, which from the point of view of classic taxonomy have been classified in 16 taxa. Only groups 3 and 4 presented intermediate characteristics. The morphologic study of the descendants showed that the regrouping of the intermediate groups had a high error rate. This fact reaffirms the condition of intermediate groups. The canonical correlation analysis between the morphologic variables of the mothers and the seedlings revealed that each morphologic group had its own association of canonical variables between mothers and their seedlings, and that the variability observed in the set of the mothers and their seedlings follows a certain order. The enormous existing morphologic diversity in the Prosopis populations of the semi-arid Chaco of the north of Córdoba and southeast of Santiago del Estero was ordered in five morphologic groups. The descendant’s morphologic studies confirmed the existence of the defined morphologic-genetic groups.展开更多
We assessed the spatial distribution of Copernicia alba Morong. In the study area, a lowland palm savanna floodplain, C. alba is the only overstory species. We hypothesized C. alba would be randomly distributed within...We assessed the spatial distribution of Copernicia alba Morong. In the study area, a lowland palm savanna floodplain, C. alba is the only overstory species. We hypothesized C. alba would be randomly distributed within natural stands. Palms were tallied in six randomly located 0.25 haplots and analyzed using a first-order, Ripley’s K function to assess the distribution of juvenile, adult, and total palm populations. While the total population had either aggregated or random distributions, when analyzing juvenile and adult population separately, we found juveniles were consistently more aggregated than the adults.展开更多
In his novel Son of Man, Augusto Roa Bastos uses images and symbols of shadows to represent the ramifications ofthe Paraguayan Dr. Jose Rodriguez de Francia＇s dictatorship. Rodriguez de Francia＇s legacy, which begin...In his novel Son of Man, Augusto Roa Bastos uses images and symbols of shadows to represent the ramifications ofthe Paraguayan Dr. Jose Rodriguez de Francia＇s dictatorship. Rodriguez de Francia＇s legacy, which begins duringthe postcolonial years and extends well into the 20th century, resonates in the novel in soeio-political structures andcharacters＇ ideologies and behaviors. It allows for plantation owners to enslave workers and their families; itconfines and oppresses people through unfounded legends and myths; and among other things, it creates a falseidea of purpose and patriotism in the Chaco War （1932-1935）, which in the end lets down the soldiers. Tocounteract these deleterious social conditions, Roa Bastos creates surreal characters, such as a fantastic helper whoaids plantation workers to escape dehumanizing situations. Roa Bastos also narrates how the people in Itapr, asmall town, make an idol of a Christ statue carved by one of their own. However, when the two Goiburfl brothersreplace the statue by crucifying their sister＇s rapist, the people＇s myth is destroyed. Likewise, Roa Bastos availshimself of Christian and Catholic concepts and symbols to transpose them into a humanistic ideology so as toconvey hope to his people through a new perspective. In this way, a new Annunciation takes place when the son ofa raped woman is born. In the end, Roa Bastos lets the course of these warped transpositions take their logicaldenouement： In the absence of a purpose beyond an earthly existence, death becomes the narrator＇s option.展开更多
Aims In the context of global change,the impacts of forest structure alter-ation on climbing plants in extra-tropical ecosystems are poorly understood.It also remains little explored,the functional strategies among cl...Aims In the context of global change,the impacts of forest structure alter-ation on climbing plants in extra-tropical ecosystems are poorly understood.It also remains little explored,the functional strategies among climbing plant species and its relationship with the local-scale distribution of climbing plant communities.Here,we aimed at three goals:(i)we studied how climbing plant community com-position responds to the modification of the original forest structure in a subtropical dry forest;(ii)we characterized climbing plant spe-cies according to functional traits related to the acquisition and use of resources;and(iii)we examined whether functional strategies at the community level are also responding to vegetation structure change,a much less addressed topic in the ecology of climbing plants.Methods The study was carried out in the Chaco forest of Córdoba Mountains,central Argentina.We selected 18 patches of‘native forests’,‘shrublands’and‘Ligustrum lucidum forests’.We counted and identified climbing plant individuals in each patch,including woody and herbaceous species.For each spe-cies,we measured 10 functional traits:leaf area,leaf area ratio,leaf dry matter content,leaf tensile strength,specific leaf area,stem density,wood saturated water content,inter-node length,petiole length and plant cover.We compared climbing plant composition,richness and abundance among the three vegeta-tion types.Then,we assessed trends of functional variation of climbing plant species by performing a principal component analysis.Finally,we investigated whether simple mean,weighted mean and Functional Richness index of principal component analysis(PCA)axes differed among the climbing plant communi-ties of the three vegetation types.Important Findings Multivariate analysis revealed that climbing plant composition of native forests significantly differed from that of shrublands and L.lucidum forests.Also,L.lucidum forests had the lowest climb-ing plant species richness.Functional variation of climbers was explained by展开更多
基于对Chaco盆地的详细解剖,通过分析其古生界天然气的成藏条件和成藏特征,总结其成藏主控因素,进而类比和分析南美前陆盆地古生界天然气的成藏特征和勘探潜力。Chaco盆地天然气资源丰富,为南美天然气储量最大的盆地,且天然气资源主要...基于对Chaco盆地的详细解剖,通过分析其古生界天然气的成藏条件和成藏特征,总结其成藏主控因素,进而类比和分析南美前陆盆地古生界天然气的成藏特征和勘探潜力。Chaco盆地天然气资源丰富,为南美天然气储量最大的盆地,且天然气资源主要集中在古生界;其古生界天然气成藏模式优越,成藏具有优生、多储、圈闭规模大、新生古储、多期成藏、近源成藏及集中分布的特征,天然气成藏受主力成藏组合和断裂的双重控制。由于构造演化的差异,南美前陆盆地古生界有效储层仅在中部3个盆地发育;除Chaco盆地外,其他2个前陆盆地古生界与Chaco盆地具有相似的天然气成藏条件,成藏背景有利,具有一定的勘探潜力。研究指出Chaco盆地古生界天然气勘探程度较高,下一步勘探仍以次安第斯带和前渊带泥盆系为主要目的层系,兼探深层和斜坡带浅层非构造圈闭。Beni盆地和Madre de Dios盆地古生界勘探程度非常低,下一步应加强断裂最为发育的次安第斯带和前渊带的勘探力度,以构造圈闭为最有利勘探目标。展开更多
文摘Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects are major factors in fragmented landscapes. Here, we examine area and edge effects and their interaction, on ensembles of arthropods associated to native vegetation in a fragmented Chaco Serrano forest. We analyzed family richness and community composition of herbivores, predators, and parasitoids on three native plant species in 12 fragments of varying size and at edge/interior positions. We also looked for indicator families by using Indicator Species Analysis. Loss of family richness with the reduction of forest fragment area was observed for the three functional groups, with sirnilar magnitude. Herbivores were richer at the edges without interaction between edge and area effects, whereas predators were not affected by edge/interior position and parasitoid richness showed an interaction between area and position, with a steeper area slope at the edges. Family composition of herbivore, predator, and parasitoid assemblages was also affected by forest area and/or edge/interior situation. We found three indicator families for large remnants and five for edges. Our results support the key role of forest area for conservation of arthropods taxonomic and functional diversity in a highly threatened region, and emphasize the need to understand the interactions between area and edge effects on such diversity.
文摘Human activities have led to global simplification of ecosystems, among which Neotropical dry forests are some of the most threatened. Habitat loss as well as edge effects may affect insect communities. Here, we analyzed insects sampled with pan traps in 9 landscapes （at 5 scales, in 100-500 m diameter circles） comprising cultivated fields and Chaco Serrano forests, at overall community and taxonomic order level. In total 7043 specimens and 456 species of hexapods were captured, with abundance and richness being directly related to forest cover at 500 m and higher at edges in comparison with forest interior. Community composition also varied with forest cover and edge^interior location. Different responses were detected among the 8 dominant orders. Collembola, Hemiptera, and Orthoptera richness and^or abundance were positively related to forest cover at the larger scale, while Thysanoptera abundance increased with forest cover only at the edge. Hymenoptera abundance and richness were negatively related to forest cover at 100 m. Coleoptera, Diptera, and Hymenoptera were more diverse and abundant at the forest edge. The generally negative influence of forest loss on insect communities could have functional consequences for both natural and cultivated systems, and highlights the relevance of forest conservation. Higher diversity at the edges could result from the simultaneous presence of forest and matrix species, although ＂resource mapping＂ might be involved for orders that were richer and more abundant at edges. Adjacent crops could benefit from forest proximity since natural enemies and pollinators are well represented in the orders showing nositive edge effects.
文摘The objective of this study consisted in the characterization of morphological variability presented in the Prosopis population in the corridor that unites the semiarid with the arid region in Argentina. In this region, four species of Prosopis get in contact (P. chilensis, P. flexuosa, P. alba and P. nigra). Due to the fact that these species make fertile hybrids, this corridor has an enormous diversity. The mother’s allowed the differentiation of five morphologic groups, which from the point of view of classic taxonomy have been classified in 16 taxa. Only groups 3 and 4 presented intermediate characteristics. The morphologic study of the descendants showed that the regrouping of the intermediate groups had a high error rate. This fact reaffirms the condition of intermediate groups. The canonical correlation analysis between the morphologic variables of the mothers and the seedlings revealed that each morphologic group had its own association of canonical variables between mothers and their seedlings, and that the variability observed in the set of the mothers and their seedlings follows a certain order. The enormous existing morphologic diversity in the Prosopis populations of the semi-arid Chaco of the north of Córdoba and southeast of Santiago del Estero was ordered in five morphologic groups. The descendant’s morphologic studies confirmed the existence of the defined morphologic-genetic groups.
文摘We assessed the spatial distribution of Copernicia alba Morong. In the study area, a lowland palm savanna floodplain, C. alba is the only overstory species. We hypothesized C. alba would be randomly distributed within natural stands. Palms were tallied in six randomly located 0.25 haplots and analyzed using a first-order, Ripley’s K function to assess the distribution of juvenile, adult, and total palm populations. While the total population had either aggregated or random distributions, when analyzing juvenile and adult population separately, we found juveniles were consistently more aggregated than the adults.
文摘In his novel Son of Man, Augusto Roa Bastos uses images and symbols of shadows to represent the ramifications ofthe Paraguayan Dr. Jose Rodriguez de Francia＇s dictatorship. Rodriguez de Francia＇s legacy, which begins duringthe postcolonial years and extends well into the 20th century, resonates in the novel in soeio-political structures andcharacters＇ ideologies and behaviors. It allows for plantation owners to enslave workers and their families; itconfines and oppresses people through unfounded legends and myths; and among other things, it creates a falseidea of purpose and patriotism in the Chaco War （1932-1935）, which in the end lets down the soldiers. Tocounteract these deleterious social conditions, Roa Bastos creates surreal characters, such as a fantastic helper whoaids plantation workers to escape dehumanizing situations. Roa Bastos also narrates how the people in Itapr, asmall town, make an idol of a Christ statue carved by one of their own. However, when the two Goiburfl brothersreplace the statue by crucifying their sister＇s rapist, the people＇s myth is destroyed. Likewise, Roa Bastos availshimself of Christian and Catholic concepts and symbols to transpose them into a humanistic ideology so as toconvey hope to his people through a new perspective. In this way, a new Annunciation takes place when the son ofa raped woman is born. In the end, Roa Bastos lets the course of these warped transpositions take their logicaldenouement： In the absence of a purpose beyond an earthly existence, death becomes the narrator＇s option.
基金This work was supported by Fondo para la Investigación Científica y Tecnológica(FonCyT,PICT 2006 N°903)Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET,PICT 11220110100873).D.E.Gurvich and M.A.Giorgis are researchers at CONICET.
文摘Aims In the context of global change,the impacts of forest structure alter-ation on climbing plants in extra-tropical ecosystems are poorly understood.It also remains little explored,the functional strategies among climbing plant species and its relationship with the local-scale distribution of climbing plant communities.Here,we aimed at three goals:(i)we studied how climbing plant community com-position responds to the modification of the original forest structure in a subtropical dry forest;(ii)we characterized climbing plant spe-cies according to functional traits related to the acquisition and use of resources;and(iii)we examined whether functional strategies at the community level are also responding to vegetation structure change,a much less addressed topic in the ecology of climbing plants.Methods The study was carried out in the Chaco forest of Córdoba Mountains,central Argentina.We selected 18 patches of‘native forests’,‘shrublands’and‘Ligustrum lucidum forests’.We counted and identified climbing plant individuals in each patch,including woody and herbaceous species.For each spe-cies,we measured 10 functional traits:leaf area,leaf area ratio,leaf dry matter content,leaf tensile strength,specific leaf area,stem density,wood saturated water content,inter-node length,petiole length and plant cover.We compared climbing plant composition,richness and abundance among the three vegeta-tion types.Then,we assessed trends of functional variation of climbing plant species by performing a principal component analysis.Finally,we investigated whether simple mean,weighted mean and Functional Richness index of principal component analysis(PCA)axes differed among the climbing plant communi-ties of the three vegetation types.Important Findings Multivariate analysis revealed that climbing plant composition of native forests significantly differed from that of shrublands and L.lucidum forests.Also,L.lucidum forests had the lowest climb-ing plant species richness.Functional variation of climbers was explained by
文摘基于对Chaco盆地的详细解剖,通过分析其古生界天然气的成藏条件和成藏特征,总结其成藏主控因素,进而类比和分析南美前陆盆地古生界天然气的成藏特征和勘探潜力。Chaco盆地天然气资源丰富,为南美天然气储量最大的盆地,且天然气资源主要集中在古生界;其古生界天然气成藏模式优越,成藏具有优生、多储、圈闭规模大、新生古储、多期成藏、近源成藏及集中分布的特征,天然气成藏受主力成藏组合和断裂的双重控制。由于构造演化的差异,南美前陆盆地古生界有效储层仅在中部3个盆地发育;除Chaco盆地外,其他2个前陆盆地古生界与Chaco盆地具有相似的天然气成藏条件,成藏背景有利,具有一定的勘探潜力。研究指出Chaco盆地古生界天然气勘探程度较高,下一步勘探仍以次安第斯带和前渊带泥盆系为主要目的层系,兼探深层和斜坡带浅层非构造圈闭。Beni盆地和Madre de Dios盆地古生界勘探程度非常低,下一步应加强断裂最为发育的次安第斯带和前渊带的勘探力度,以构造圈闭为最有利勘探目标。
